U.S. patent application number 12/673325 was filed with the patent office on 2011-09-01 for allocating method of moving area list of user equipment and corresponding apparatus.
This patent application is currently assigned to Datang Mobile Communications Equipment Co., Ltd.. Invention is credited to Yihua Jiang, Huarui Liang, Chunshan Xiong, Hui Xu.
Application Number | 20110210845 12/673325 |
Document ID | / |
Family ID | 40377823 |
Filed Date | 2011-09-01 |
United States Patent
Application |
20110210845 |
Kind Code |
A1 |
Xiong; Chunshan ; et
al. |
September 1, 2011 |
ALLOCATING METHOD OF MOVING AREA LIST OF USER EQUIPMENT AND
CORRESPONDING APPARATUS
Abstract
A method of allocating the moving area list of user equipment
which relating to wireless communication technology. Interacting
signaling between network and UE is reduced. The utilization
efficiency of network resource is enhanced. The method includes,
receiving the area ID which is pre-defined from UE, acquiring the
history information of the last allocated moving area list from the
mobility management entity (MME) which allocated the last moving
area list, allocating new moving area list according to the history
information and the received area ID. Accordingly, a MME and UE are
disclosed.
Inventors: |
Xiong; Chunshan; (Beijing,
CN) ; Jiang; Yihua; (Beijing, CN) ; Liang;
Huarui; (Beijing, CN) ; Xu; Hui; (Beijing,
CN) |
Assignee: |
Datang Mobile Communications
Equipment Co., Ltd.
Beijing
CN
|
Family ID: |
40377823 |
Appl. No.: |
12/673325 |
Filed: |
August 15, 2008 |
PCT Filed: |
August 15, 2008 |
PCT NO: |
PCT/CN08/01479 |
371 Date: |
March 10, 2010 |
Current U.S.
Class: |
340/539.13 |
Current CPC
Class: |
H04W 8/20 20130101; H04W
60/00 20130101 |
Class at
Publication: |
340/539.13 |
International
Class: |
G08B 1/08 20060101
G08B001/08 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 15, 2007 |
CN |
200710120319.8 |
Claims
1. A method for allocating a new Tracking Area List for a User
Equipment, comprising: receiving a designated Tracking Area
Identity from the User Equipment; obtaining history information
when an old Tracking Area List is allocated from an old Mobility
Management Entity allocating the old Tracking Area List; and
allocating a new Tracking Area List for the User Equipment
according to the obtained history information and the received
designated Tracking Area Identity.
2. The method of claim 1, wherein allocating the new Tracking Area
List for the User Equipment comprises: determining a movement
direction of the User Equipment according to a Tracking Area
Identity of the Tracking Area where the User Equipment is currently
allocated and the received designated Tracking Area Identity;
estimating a movement speed of the User Equipment according to the
obtained history information, and allocating the new Tracking Area
List for the User Equipment according to the determined movement
direction and the estimated movement speed of the User
Equipment.
3. The method of claim 1, wherein the designated Tracking Area
Identity from the User Equipment is the Tracking Area Identity of
the Tracking Area where User Equipment is located when a Tracking
Area having a TA ID within the old Tracking Area List is accessed
for the last time.
4. The method of claim 3, wherein the User Equipment stores and
updates the Tracking Area Identity of each Tracking Area to which
the User Equipment moves during its the movement within the
Tracking Areas having identities within the old Tracking Area
List.
5. The method of claim 4, wherein the User Equipment stores the
Tracking Area Identity of the Tracking Area to which it moves into
its Universal Subscriber Identity Module or nonvolatile
storage.
6. The method of claim 2, wherein the history information
comprises: allocation time when the old Tracking Area List is
allocated and a Tracking Area Identity of the Tracking Area where
the User Equipment is located when the old Tracking Area List is
located.
7. The method of claim 6, wherein estimating the movement speed of
the User Equipment according to the obtained history information
comprises: calculating a time interval between the current time and
the allocation time when the old Tracking Area List is allocated;
calculating a distance between a Tracking Area where the User
Equipment is currently located and a Tracking Area where the User
Equipment is located when the old Tracking Area List is allocated,
according the Tracking Area Identity of the Tracking Area where the
User Equipment is currently located and the Tracking Area Identity
of the Tracking Area where the User Equipment is located when the
old Tracking Area List is allocated; and estimating the movement
speed of the User Equipment according to the calculated time
interval and the estimated distance.
8. The method of claim 7, wherein the history information further
comprises the old Tracking Area List allocated to the User
Equipment.
9. The method of claim 8, wherein estimating the movement speed of
the User Equipment according to the obtained history information
further comprises: determining whether the calculated time interval
is shorter than the preset time interval; determining a weight used
for adjusting the movement speed of the User Equipment based on the
old Tracking Area List allocated for the User Equipment if the
calculated time interval is shorter than the preset time interval;
and adjusting the estimated movement speed of the User Equipment by
using the determined weight.
10. The method of claim 9, wherein the preset time interval is
N*MRC_Timer, wherein N denotes a natural number and MRC_Timer
denotes a time parameter set by a Mobile Reachable Timer of the
User Equipment.
11. The method of claim 1, wherein after allocating the old
Tracking Area List for the User Equipment, a Mobility Management
Entity allocating the old Tracking Area List stores the history
information into User Equipment Context corresponding to the User
Equipment.
12. The method of claim 1, wherein the User Equipment stores the
new Tracking Area List allocated into a volatile or nonvolatile
storage, and indicates the Tracking Area List as invalid or deletes
the Tracking Area List after the User Equipment is detached or
powered off.
13. A Mobility Management Entity, comprising: a Tracking Area
Identity receiving unit adapted to receive a designated Tracking
Area Identity from a User Equipment; a history information
obtaining unit adapted to obtain history information when the old
Tracking Area List is allocated from the old Mobility Management
Entity allocating the old Tracking Area List; and a Tracking Area
List allocating unit adapted to allocate a new Tracking Area List
for the User Equipment according to the obtained history
information and the received designated Tracking Area Identity.
14. The Mobility Management Entity of claim 13, wherein the
Tracking Area List allocating unit comprises: a subunit adapted to
determine a movement direction of the User Equipment according to
the Tracking Area Identity of the Tracking Area where the User
Equipment is currently located and the designated Tracking Area
Identity sent by the User Equipment; a subunit adapted to estimate
the movement speed of the User Equipment according to the obtained
history information; and a subunit adapted to allocate a new
Tracking Area List according to the determined movement direction
of the User Equipment and the estimated movement speed of the User
Equipment.
15. The Mobility Management Entity of claim 14, wherein the history
information obtained by the history information obtaining unit
comprises: allocation time when the old Tracking Area List is
allocated and a Tracking Area Identity of the Tracking Area where
the User Equipment is located when the old Tracking Area List is
located.
16. The Mobility Management Entity of claim 15, wherein the subunit
adapted to estimate the movement speed of the User Equipment
according to the obtained history information comprise: a subunit
adapted to calculate a time interval between the current time and
the allocation time when the old Tracking Area List is allocated; a
subunit adapted to calculate a distance between a Tracking Area
where the User Equipment is currently located and a Tracking Area
where the User Equipment is located when the old Tracking Area List
is allocated, according the Tracking Area Identity of the Tracking
Area where the User Equipment is currently located and the Tracking
Area Identity of the Tracking Area where the User Equipment is
located when the old Tracking Area List is allocated; and a subunit
adapted to estimate the movement speed of the User Equipment
according to the calculated time interval and the estimated
distance.
17. The Mobility Management Entity of claim 16, wherein the history
information obtained by the history information obtaining unit
further comprises: the old Tracking Area List allocated to the User
Equipment, and the subunit adapted to estimate the movement speed
of the User Equipment according to the obtained history information
further comprises: a subunit adapted to determine whether the
calculated time interval is shorter than the preset time interval;
a subunit adapted to determine a weight used for adjusting the
movement speed of the User Equipment based on the old Tracking Area
List allocated for the User Equipment if the calculated time
interval is shorter than the preset time interval; and a subunit
adapted to adjust the estimated movement speed of the User
Equipment by using the determined weight.
18. (canceled)
19. A User Equipment comprising: a receiving unit, which is adapted
to receive a Tracking Area Identity of the Tracking Area where the
User Equipment is currently located, and receive a Tracking Area
List allocated by a Mobility Management Entity; a Tracking Area
List information storage and update unit, which is adapted to store
and update the Tracking Area List allocated by the Mobility
Management Entity according to the Tracking Area List received by
the receiving unit; a Tracking Area Identity storage and update
unit, which is adapted to store and update a Tracking Area Identity
of the Tracking Area where the User Equipment is currently located
according to each Tracking Area Identity received by the receiving
unit, during the movement of the User Equipment within Tracking
Areas having identities within the old Tracking Area List; and a
sending unit, which is adapted to send to the Mobility Management
Entity the Tracking Area Identity stored and updated by the
Tracking Area Identity storage and update unit.
20. The User Equipment of claim 19, wherein the Tracking Area
Identity storage and update unit stores and updates the Tracking
Area Identity in a nonvolatile storage.
21. The User Equipment of claim 19, wherein the Tracking Area List
information storage and update unit comprises: a subunit adapted to
store the Tracking Area List in the volatile or nonvolatile
storage; and a subunit adapted to indicate the Tracking Area List
stored in the volatile or nonvolatile storage as invalid or delete
the Tracking Area List when the User Equipment is detached or
powered off.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to wireless communication
technologies in the field of communications, and particularly to a
method for allocating a tracking area list of a User Equipment, a
Mobility Management Entity and a User Equipment.
BACKGROUND OF THE INVENTION
[0002] In a mobile communication system, the mobility management of
a User Equipment (UE) is a fundamental and necessary logical
function of the mobile communication network.
[0003] For the purpose of addressing and identifying the UE in the
mobility management, a Core Network (CN) divides a network into a
series of areas in terms of logical architecture, and allocates a
separate identity for each of the areas. Depending on the division
criteria, the network is divided into different areas, including,
for example, a Tracking Area (TA) and a Routing Area (RA) provided
with a Tracking Area Identity (TA ID) and a Routing Area Identity
(RA ID) respectively.
[0004] For the sake of simplification, the reference to an area
below is made by taking the Tracking Area as an example.
[0005] The Core Network allocates a specific area (which is
indicated by at least one TA ID) for a DE attached to the network,
and when the DE moves from the current allocated area to an
unallocated area, the UE initiates the TA Update procedure to the
network.
[0006] A Mobility Management Entity (MME) in the Core Network is
responsible for the mobility management of the UE, and the MME
includes, but not limited to a Mobile Switching Center (MSC), a
Serving GPRS Support Node (SGSN), and a signaling terminating node
at a non-access layer of a core network of the Evolved Packet
System (EPS) of the Third Generation Partnership Project
(3GPP).
[0007] The Core Network includes a plurality of MMEs, each of which
manages a certain range of areas, that is, each MME manages a
limited range of areas. It is possible for a UE to move out of an
area allocated by the current MME to the UE, and further move out
of the entire areas managed by the current MME.
[0008] In the traditional 3G mobile communication system, since the
MME allocates to the UE a single TA ID, i.e. one TA, the UE may
traverse multiple TAs within a short period of time when moving at
a high speed, as a result, multiple TA update procedures are
caused, signaling exchanged between the network and the UE is
increased greatly, and network resources are wasted.
[0009] In view of the above, an MME allocates a TA List containing
multiple TA IDs to a UE in the 3GPP EPS system. Since the TA List
includes multiple TA IDs, the range of areas allocated for the UE
is increased, so that the TA updates during the movement of the UE
are reduced and the utilization of the network resources are
improved.
[0010] To allocate a TA List for the UE, it is necessary for the
MME to determine as possible the area that the UE is moving to so
that an appropriate TA List is allocated to the UE in order to
reduce as possible the location updates caused during the fast
movement of the UE.
[0011] At present, however, the MME allocates a new TA List for the
UE based on a single TA ID in the original TA List that is sent by
the UE, which is insufficient for the MME to allocate a new
appropriate TA List for the UE. Therefore, the areas allocated by
the MME for the UE are possibly inappropriate and multiple location
updates are caused during the fast movement of the UE, thus, a
large amount of signaling is still exchanged between the network
and the UE, and the network processing resources are still
wasted.
SUMMARY OF THE INVENTION
[0012] Embodiments of the invention provide a method and apparatus
for allocating a Tracking Area List for a User Equipment, to reduce
the amount of signaling exchanged between the network and the User
Equipment and improve the utilization of network resources.
[0013] An embodiment of the invention provides a method for
allocating a new Tracking Area List for a User Equipment,
including: receiving a designated Tracking Area Identity from the
User Equipment; obtaining history information when old Tracking
Area List is allocated from an old Mobility Management Entity
allocating the old Tracking Area List; and allocating a new
Tracking Area List for the User Equipment according to the obtained
history information and the received Tracking Area Identity.
[0014] An embodiment of the invention provides a Mobility
Management Entity, including: a Tracking Area Identity receiving
unit adapted to receive a designated Tracking Area Identity from a
User Equipment; a history information obtaining unit adapted to
obtain history information when the old Tracking Area List is
allocated from an old Mobility Management Entity allocating the old
Tracking Area List; and a Tracking Area List allocating unit
adapted to allocate a new Tracking Area List for the User Equipment
according to the obtained history information and the received
Tracking Area Identity.
[0015] An embodiment of the invention provides a User Equipment
including: a receiving unit, which is adapted to receive a Tracking
Area Identity of the Tracking Area where the User Equipment is
currently located, and receive a Tracking Area List allocated by a
Mobility Management Entity; a Tracking Area List information
storage and update unit, which is adapted to store and update the
Tracking Area List allocated by the Mobility Management Entity
according to the Tracking Area List received by the receiving unit;
a Tracking Area Identity storage and update unit, which is adapted
to store and update a Tracking Area Identity of the Tracking Area
where the User Equipment is currently located according to each
Tracking Area Identity received by the receiving unit, during the
movement of the User Equipment within Tracking Areas covered by the
current allocated Tracking Area List; and a sending unit, which is
adapted to send to the Mobility Management Entity the Tracking Area
Identity stored and updated by the Tracking Area Identity storage
and update unit.
[0016] In embodiments of the invention, the history information
when the old TA List is allocated is added to the UE Context of the
old MME allocating the old TA List, and the specific TA ID is sent
by the UE to the new MME which is to allocate a new TA List, so
that the movement direction and movement speed of the UE is
estimated appropriately based on the history information and the TA
ID during the allocation of a new TA List, thus an appropriate TA
List is allocated to the UE, thereby reducing the amount of
signaling exchanged between the network and the UE and improving
the utilization of network resources.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 is a schematic diagram showing a TA List according to
an embodiment of the invention;
[0018] FIG. 2 is a schematic diagram showing the structure of a
Mobility Management Entity according to an embodiment of the
invention; and
[0019] FIG. 3 is a schematic diagram showing the structure of a
User Equipment according to an embodiment of the invention.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0020] As can be seen from the discussion in the background, to
allocate a relatively appropriate Tracking Area List for a UE, an
MME is required to estimate the area that the UE is heading for and
the movement speed of the UE. At present, however, depending on one
TA ID is sent by the UE, the MME cannot satisfy the requirements of
estimating the area that the UE is heading for and the movement
speed of the UE and then allocating an appropriate Tracking Area
List for the DE. Therefore, in an embodiment of the invention, in
order to allocate an appropriate new Tracking Area List for the UE,
some history information of the old allocated Tracking Area List
(i.e. the Tracking Area List allocated for the UE just before any
new Tracking Area List is allocated) is respectively stored in the
old MME and the UE, enabling the new MME to estimate the area that
the UE is heading for and the movement speed of the UE, thereby
reducing the amount of signaling exchanged between the UE and
network side during the fast movement of the UE and improving the
utilization of the network resources.
[0021] Preferably, given that the old MME which has allocated the
old Tracking Area List for the UE is denoted by MME 1 and the new
MME which allocates a subsequent new Tracking Area List for the UE
is denoted by MME 2, MME 1 and MME 2 may be physically the same MME
or different MMEs. During the mobility management, which may
include for example a TA update procedure and an attachment
procedure, when the UE accesses MME 2, the UE provides a TA ID from
its old Tracking Area List for MME 2; in this case, MME 2 receives
the TA ID provided by the UE, obtains the UE Context from MME 1,
and allocates a new Tracking Area List for the DE based on the TA
ID provided by the UE and the UE Context obtained from MME 1. In
view of this, in an embodiment of the invention, some additional
history information when the old Tracking Area List is allocated is
stored by MME 1 in the UE Context in MME 1, and the TA ID sent by
the UE to the MME 2 is further defined, to thereby enable MME 2 to
allocate a relatively appropriate new Tracking Area List for the UE
based on the history information in the UE Context and the further
defined TA ID.
[0022] The implementation, embodiments and corresponding beneficial
effects of the solution of the invention are described below in
detail in connection with the Drawings.
[0023] An implementation of the invention includes: receiving a
designated TA ID sent by a UE; obtaining history information when
the old Tracking Area List is allocated from the old Mobility
Management Entity which has allocated the old Tracking Area List;
and allocating a new Tracking Area List for the UE based on the
obtained history information and the received TA ID.
[0024] The history information refers to such information that is
used for determining the area traversed by the UE, the movement
speed of the UE, the direction in which the UE is moving, and so
on, and includes, but not limited to the old allocated Tracking
Area List (the following description is given by taking the TA List
as an example), the time when the old TA List is allocated, the TA
ID of the TA where the UE is located when the old TA List is
allocated, and so on.
[0025] Further, since the TA ID received by the new MME in the
prior art is disadvantageous for determining the area that the UE
is heading for, the TA ID from the UE is such defined in an
embodiment of the invention that the TA ID sent by the UE is a
specific TA ID in the old TA List, for example, the TA ID of the TA
where the UE is located when the area covered by the old TA List is
visited for the last time, i.e. the Last Visited Registered
TAI.
[0026] Since the UE Context is stored in the MME, the MME can store
the history information above to its stored DE Context after
allocating a TA List for the UE. Examples of storing the history
information to the UE Context by the MME are described below, and
an additional parameter is added as history information depending
on actual application in particular embodiments.
[0027] After allocating the old TA List (i.e. the allocated TA List
just preceding any new TA List is allocated) for the UE, MME 1
stores the allocated old TA List, the allocation time of the old TA
List, and the TA ID of the TA where the UE is located when the old
TA List is allocated, in the UE Context corresponding to the
UE.
[0028] To allocate a new TA List for the UE, MME 2 calculates a
time interval between the current time and the old allocation time
when MME 1 allocates the old TA List that is obtained from the UE
Context stored in MME 1, and determines a distance between the TA
where the UE is currently located and the TA where the UE is
located when the old TA List is allocated by MME 1, based on the TA
ID of the TA where the UE is located when the old TA List is
allocated that is obtained from the UE Context.
[0029] Subsequently, MME 2 estimates the movement speed of the UE
based on both the time interval and the distance that are
determined above. If the UE covers a relatively long distance
within a relatively short time interval, the movement speed of the
DE is determined as high, and thus a new TA List with a relatively
large coverage is allocated for the UE; otherwise, if the UE covers
a relatively short distance within a relatively long time interval,
the movement speed of the UE is determined as low, and thus a TA
List with a relatively small coverage is allocated for the UE.
[0030] If the UE does not move directly from the old TA where the
UE is located when the old TA List is allocated by MME 1 to the TA
where the UE is currently located (for example, the UE moves from
the old TA to another TA and then to the current allocated TA), an
error may be present in the movement speed of the UE determined
above. In this case, the movement speed is adjusted based on the
old TA List allocated by MME 1 to decrease the error. For example,
a weight is determined with reference to the allocated old TA List,
and the movement speed is multiplied by the weight to decrease the
error in the movement speed. Therefore, the old TA List allocated
by MME 1 is required to be added to the UE Context. The
significance of the old TA List allocated by MME 1 is related to
the time interval obtained above. Typically, the smaller the time
interval is, the more significant the old TA List is; vice versa,
the longer the time interval is, the less significant the old TA
List is. For example, when the time interval obtained above is one
week, the old TA List is substantially of no significance, and
generally cannot be used for estimating the movement speed of the
UE; and when the time interval obtained above is five minutes, the
old TA List is referred to for the calculating of the movement
speed of the UE.
[0031] For the calculation of the time interval above, the time of
MME 1 needs to be in synchronization with that of MME 2, otherwise,
the time interval calculated may be inaccurate. However, such
synchronization need not have a high precision, and synchronization
in the order of a second satisfies embodiments of the invention.
Various manners can be used for synchronization in the prior art,
for example, the synchronization in the order of a second is
implemented through the Network Time Protocol (NTP) defined by the
Internet Engineering Task Force (IETF).
[0032] As describe above, to enable MME 2 to determine whether it
is necessary to refer to the old TA List for the allocation of a
new TA List for the UE with respect to a certain range of time
interval, it is possible to define such a rule that MME 2 refers to
the old TA List for the allocation of a new TA List for the UE if
the obtained time interval is shorter than or equal to a preset
time interval, and otherwise, MME 2 does not refer to the old TA
List that has been allocated by MME 1. Here, the preset time
interval is set by the operator on its own initiative in various
ways, for example, the preset time interval is set as N*MRC_Timer,
where N denotes a natural number and MRC_Timer denotes the time set
by a Mobile Reachable timer of the DE, and the operator sets the
value of N and MRC_Timer depending on a practical application.
[0033] In addition to the history information as described above, a
movement track of the UE is important for allocating a new TA List
for the UE. Currently, a single TA ID is sent by the UE to the new
MME and it is impossible to obtain an accurate movement track of
the UE by using the single TA ID. However, the TA ID to be sent by
the UE is further such defined that a specific TA ID that
facilitates the determination of the movement direction of the UE
is sent by the UE, for example, the UE sends the TA ID of the TA
located for the last time within the old TA List allocated by MME
1, i.e. the Last Visited Registered TM, so that the movement
direction of the UE is determined by MME 2 by combining the
designated TA ID sent by the UE and the TA ID of the TA where the
UE is currently located. Particularly in an embodiment of the
invention, when moving within the areas covered by the old TA List,
the UE stores the TA ID of each TA where it accesses into its
Universal Subscriber Identity Module (USIM) or nonvolatile storage
of the DE although no TA update occurs, and replaces a previous TA
ID if the previous TA ID is already stored. In this way, when a TA
update procedure is initiated by the UE, the TA ID currently stored
in the UE is the TA ID of the TA where the UE is located when the
old TA List is accessed for the last time, and MME 2 determines the
movement direction of the UE by referring to both the designated TA
ID provided by the UE and the TA ID of the TA where the UE is
currently located, thereby facilitating the allocation of a new
relatively appropriate TA List for the UE.
[0034] FIG. 1 is a schematic diagram showing the TA List according
to an embodiment of the invention. An embodiment of allocating a
new TA List is described below in connection with FIG. 1.
[0035] When a UE moves to an area TA1, MME 1 allocates a TA List of
"TA1, TA2, . . . , TA6" for the UE, and then adds the allocated TA
List, the allocation time of the TA List and the TA ID of the TA
where the UE is located when the TA List is allocated (i.e. TA1) to
the UE Context corresponding to this UE; in addition, the UE stores
the TA ID of the TA where it is currently located (i.e. TA1) into
its USIM or nonvolatile storage, and stores the allocated TA List
into its volatile storage such as a memory.
[0036] Since the network side allocates a new TA List for a DE when
the UE attaches to the network again after its detachment (such as
power off), it is preferable in the embodiment of the invention to
store the allocated TA List into the volatile storage of the UE,
that is, the TA List does not exist in the UE after the detachment
of the UE. Alternatively, the TA List is stored in the nonvolatile
storage of the UE.
[0037] When moving out of the area TA1, the UE determines whether
the TA ID of the TA where it moves to is within the old TA List, if
so, the UE does not initiate a TA update and stores the TA ID of
the TA where it moves to into its USIM or nonvolatile storage to
replace the existing TA 1. If the UE determines that the TA ID of
the TA where it moves to is not within the old TA List, a TA update
procedure is initiated, after the TA Update procedure is finished,
the UE stores the TA ID of the TA where it moves to into its USIM
or nonvolatile storage after the TA update.
[0038] For example, when moving to an area TA2, the DE determines
that TA2 is within the old TA List and conducts no TA update, and
stores the TA ID of the TA where it is currently located (i.e. TA2)
into its USIM or nonvolatile storage to replace TA1.
[0039] Likewise, when the UE moves further to an area TA3, the UE
stores TA3 into its USIM or nonvolatile storages to replace
TA2.
[0040] When moving further to an area TA7, the UE determines that
TA7 is not within the old TA List including TA1-TA6, and then sends
to MME 2 a TA Update Request message, which contains a TA ID (i.e.
TA3) stored in the USIM or nonvolatile storage of the UE and an EPS
Temporary Mobile Station Identity (S-TMSI).
[0041] After receiving the TA Update Request message from the UE,
MME 2 locates MME 1 according to the TA3 and S-TMSI contained in
the message, obtains the UE Context corresponding to the UE from
MME 1, and extracts the old TA List (i.e. TA1-TA6), the allocation
time of the old TA List and the TA ID of the TA where the UE is
located when the old TA List is allocated from the UE Context.
[0042] In the case that MME 2 and MME 1 are the same MME
physically, after receiving the TA Update Request message from the
UE, MME 2 locates MME 1 according to the S-TMSI contained in the
message, searches for the UE Context corresponding to the UE in the
located MME 1, and extracts the old TA List (i.e. TA1-TA6), the
allocation time of the old TA List and the TA ID of the TA where
the UE is located when the old TA List is allocated from the UE
Context.
[0043] Subsequently, MME 2 allocates a new TA List for the UE
according to the history information extracted as described above
as follows.
[0044] According to the current time and the extracted allocation
time of the old TA List allocated by MME 1, MME 2 calculates the
time interval between the current time and time when the old TA
List is allocated by MME 1, and determines whether the time
interval is shorter than the preset time interval; if so, MME 2
allocates a new TA List for the UE with reference to the extracted
old TA List; otherwise, MME 2 allocates a new TA List for the UE
without reference to the extracted old TA List. It is assumed that
the calculated time interval is shorter than the preset time
interval in the embodiment, and the extracted old TA List is used
for the allocation of the new TA List.
[0045] Then, MME 2 estimates the movement speed of the UE by using
the distance between the areas TA1 and TA7 (for example, the
distance is calculated from related parameters configured by the
operator) and the calculated time interval, determines a weight
according to the extracted old TA List, and adjusts the estimated
movement speed based on the determined weight to obtain a more
accurate movement speed.
[0046] If the adjusted movement speed is relatively high, it is
determined to allocate a relatively large coverage for the UE;
otherwise, a relatively small coverage is allocated for the UE. It
is assumed that the determined movement speed of the UE is low in
the embodiment, and hence MME 2 determines to allocate a relatively
small coverage of Tracking Areas, e.g. three TAs, for the UE.
[0047] Subsequently, according to the area TA3 provided by the UE
in the TA update request message and TA7 where the UE initiates the
TA update procedure, MME 2 determines that the UE is moving in an
inclining direction from the area TA3 to area TA7, and hence
allocates Tracking Areas for the UE along such direction.
[0048] In this case, MME 2 allocates a new TA List, i.e. a TA List2
of "TA3, TA7, TA8", for the UE.
[0049] After allocating TA List2 for the UE, MME 2 adds the
allocated TA List2, the allocation time of the TA List2, and the TA
ID of the TA (i.e. TA7) where the UE is located when the TA List2
is allocated to the UE Context, replacing the existing history
information.
[0050] Additionally, the UE determines that TA7 is contained in the
new allocated TA List2, stores TA7 in the USIM or nonvolatile
storage of the UE to replace TA3, and stores the TA List2 into the
memory of the UE to replace the old TA List allocated by MME 1
previously.
[0051] Thus, the allocation of the new TA List is completed.
[0052] Corresponding to the method for allocating the TA List
described above, an embodiment of the invention further provides a
Mobility Management Entity. FIG. 2 is a schematic diagram showing
the structure of the Mobility Management Entity according to an
embodiment of the invention, as shown, the Mobility Management
Entity 10 includes:
[0053] a Tracking Area Identity receiving unit 11 which is adapted
to receive a designated TA ID from a UE;
[0054] a history information obtaining unit 12 which is adapted to
obtain history information when the old TA List is allocated from a
old Mobility Management Entity allocating the old TA List; and
[0055] a Tracking Area List allocating unit 13 which is adapted to
allocate a new TA List for the UE according to the obtained history
information and the received designated TA ID.
[0056] If the old TA List, the allocation time of the old TA List
and the TA ID of the TA where the UE is located when the old TA
List is allocated are included in the history information, the
Tracking Area List allocating unit 13 estimates the movement speed
of the UE according to the allocation time and the TA ID when the
new TA List is allocated, and determines the moving direction of
the UE according to the TA ID of the TA where the UE is currently
located and the designated TA ID sent by the UE. Thus, the Tracking
Area List allocating unit 13 includes:
[0057] a subunit adapted to determine the movement direction of the
UE according to the TA ID of the TA where the UE is currently
located and the designated TA ID sent by the UE;
[0058] a subunit adapted to estimate the movement speed of the UE
according to the obtained history information; and
[0059] a subunit adapted to allocate a new TA List according to the
determined movement direction of the UE and the estimated movement
speed of the UE.
[0060] The subunit adapted to estimate the movement speed of the UE
according to the obtained history information includes:
[0061] a subunit adapted to calculate a time interval between the
current time and the allocation time when the new Tracking Area
List is allocated;
[0062] a subunit adapted to calculate a distance between a Tracking
Area where the UE is currently located and a Tracking Area where
the UE is located when the old Tracking Area List is allocated,
according the Tracking Area Identity of the Tracking Area where the
UE is currently located and the Tracking Area Identity of the
Tracking Area where the UE is located when the old Tracking Area
List is allocated; and
[0063] a subunit adapted to estimate the movement speed of the UE
according to the calculated time interval and the estimated
distance.
[0064] Additionally, since the UE might move to the same TA again
during the movement within the areas covered by the old TA List, an
error may be present in the movement speed of the UE estimated
according to the above allocation time and the TA ID of the TA
where the UE is located at the allocation time. In this case, the
movement speed is adjusted based on the old TA List by the subunit
which is adapted to estimate the movement speed of the UE according
to the obtained history information.
[0065] However, since the significance of the old TA List is in
inverse proportion to the time interval between the allocation time
of the old TA List and the current time, it is necessary to
calculate the time interval to determine the significance of the
old TA List, and further to adjust the movement speed described
above more accurately. Thus, the subunit adapted to estimate the
movement speed of the UE according to the obtained history
information further includes:
[0066] a subunit adapted to determine whether the calculated time
interval is shorter than the preset time interval;
[0067] a subunit adapted to determine a weight used for adjusting
the movement speed of the UE based on the old Tracking Area List
allocated for the UE if the calculated time interval is shorter
than the preset time interval; and
[0068] a subunit adapted to adjust the estimated movement speed of
the UE by using the determined weight.
[0069] Here, the preset time interval is set according to a
practical implementation, and is set as, but not limited to
N*MRC_Timer, where N denotes a natural number and MRC_Timer denotes
a time parameter set by a Mobile Reachable Timer of the UE.
[0070] Further, after allocating a new TA List for the UE, the MME
needs to store the related history information to the UE Context
corresponding to the UE.
[0071] An embodiment of the invention further provides a User
Equipment. FIG. 3 is a schematic diagram showing the structure of a
User Equipment according to an embodiment of the invention, as
shown, the User Equipment 20 includes:
[0072] a receiving unit 21, which is adapted to receive a Tracking
Area Identity of the Tracking Area where the User Equipment is
currently located, and receive a Tracking Area List allocated by a
Mobility Management Entity;
[0073] a Tracking Area List information storage and update unit 22,
which is adapted to store and update the Tracking Area List
allocated by the Mobility Management Entity according to the
Tracking Area List received by the receiving unit 21;
[0074] a Tracking Area Identity storage and update unit 23, which
is adapted to store and update a Tracking Area Identity of the
Tracking Area where the User Equipment is currently located
according to each Tracking Area Identity received by the receiving
unit 21, during the movement of the User Equipment within Tracking
Areas covered by the old allocated Tracking Area List; and
[0075] a sending unit 24, which is adapted to send to the Mobility
Management Entity the Tracking Area Identity stored and updated by
the Tracking Area Identity storage and update unit 23.
[0076] The TA List stored and updated by the Tracking Area List
information storage and update unit 22 is stored in a volatile
storage (such as a memory) or a nonvolatile storage of the User
Equipment. Further, since the TA List is no longer used after the
detachment or power off of the User Equipment, it is preferable to
store the received TA List in the volatile storage such as the
memory of the User Equipment, and the stored TA List is lost
automatically when the User Equipment is powered off.
[0077] In either case that the TA List is stored in a volatile
storage or a nonvolatile storage, the UE deletes the TA List or
indicate the TA List as invalid, and the TA List is no longer used.
Accordingly in this case, the Tracking Area List information
storage and update unit 22 includes:
[0078] a subunit adapted to store the Tracking Area List in the
volatile or nonvolatile storage; and
[0079] a subunit adapted to indicate the Tracking Area List stored
in the volatile or nonvolatile storage as invalid or delete the
Tracking Area List when the User Equipment is detached or powered
off
[0080] The Tracking Area Identity storage and update unit 23 stores
the TA ID into the USIM or nonvolatile storage of the UE.
[0081] It shall be noted that the above embodiments are merely used
to illustrate the solution of the invention without limitation.
While the invention has been described with reference to the
embodiments, it will be appreciated by those skilled in the art
that various modifications and alterations may be made to the
solutions in the embodiments of the invention without departing
from the scope of the invention.
* * * * *